Got a 3 beep alarm on SB engine, when we came to the 1st Manatee zone, on Saturday, running with HP PB club to Grills. Idled thru zone with SB engine off, fired her up, no 3 beep alarm, jumped on plane, got over the channel into Grills, and SB coolant temp went to 190, got alarm and light. SB oil temp good. Ran temp of 180 -190 on the way back to the house. Flushed engines, SB right at 190. Check SB engine next morning, just turning key on, SB coolant temp gauge to 140 on COLD engine. Disconnected sensor, turned key on, gauge stays at 100, got 3 beep alarm again. Hooked sensor back up, and 140, and no 3 beep alarm. Got scan tool out, NO COOLANT Temp related faults! Anyway, 99.9 % sure it's the coolant temp sensor/sender, and read my 600SCi manual on how to replace, Holy crap, got pull the heat exchanger to replace sensor! Is there any easier way to do this guys? Has any 600SCI's owners had to do this replacement yet? Please see attached diagram showing location it's F/N 39, (Thanks BAM marine for diagram.)

Morning guys, still looking for any input/ideas..... the 525 uses the same sensor/location, did any of you 525 owners have to do this yet?
Thanks in advance.
Dean

I haven't had to replace one on my 700's (yet), but I do carry a spare. However, replacing it would just about ruin a weekend (time-wise).

I know you have the supercharger, so it's not as simple as a NA motor, but after you remove the belt and tensioner getup, it shouldn't be too hard to pull out.

Can you see the sensor if you lift the coolant reservoir off? Perhaps you can get to it with a crowfoot wrench?

S,
Yeah that's kinda the approach I'm going to take... Ordered the sensor today
Thanks,
Dean

Well, quick update, I had to remove the heat exchanger, what a pain in the a$$.... Ridiculous that Merc designed that location for this sensor. Going to finish up today, it took about 4 hours to just replace the sensor, now I have to finish putting it all back together....

Only suggestion I have is could the engine be running hot and sensor is being truthful?

Nope...

Check SB engine next morning, just turning key on, SB coolant temp gauge to 140 on COLD engine.